Hi all, before I send my SN3 in for service I was hoping to get further insights into the problem. My SN3 has developed an intermittent hum through the right speaker. The hum is not effected by source, volume or mute. Powering the unit off->on almost always clears the problem and then it can recur soon or days later.
Have you disconnected and reconnected everything in case it was a poor connection?
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If your speaker cables run parallel to each other, try seperating them by a few inches all the way along & see if the problem persists.
Regards
Neil.
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Funny I was going to say something like this.
The other day I had to rebuild my system and my SN3 was humming. It’s never done this before. The solution was to re-seat my speaker cables albeit I had them reversed and I made sure they weren’t near any power cables. Problem solved.
The Service Dept. listening room has a slightly odd arrangement, in that the passive crossovers for our SL2s are located at the opposite end of the room to the speakers. This makes it easier to integrate Snaxos for listening.
Some SN3s take exception to the odd load this represents & can fall into oscillation. Seperating the cables that lead to the passive crossovers certainly helps to resolve the issue.
Regards
Neil.
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I have considered the possibility of inductance caused by speaker cables and or cabling. That said, I try to separate or run at right angles when cables overlap. Probably should try a different set of spkr. cables. I was wondering if perhaps a leaky blocking cap might be at fault as mute has no effect. The additional difficulty is that it can take several days to act up or it can happen much sooner.
I don’t think that this makes a difference but it happens with or without my HiCap DR
I’m wondering whether it just doesn’t like the non-Naim bi-wire speaker cable. As you have posted above, I would try it with some suitable length NACA5 or something closer to Naim’s recommended spec.
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A hum that disappears when you turn off the SN3 and reappears randomly at a later time suggests a bad capacitor in the amp somewhere. Is the hum dependent upon the volume control or not?
It is not dependent on source, volume or mute, which is why I speculated a blocking cap. I assume that this would be after the mute circuit, but this is an uneducated stab in the dark.
If there is an inductance problem from my speaker cables it seems logical that it would not be limited to the right channel?
When the right speaker is making the noise, unplug the left speaker & see if it stops.
Regards
Neil.
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Will try that.
Narrows it down some. If it’s in the amp. it’s probably in the power output stage. At this point, I’m guessing its time for a flight back to the mother ship!
Yeah, the only issue is it can happen in a day or 2 or go a week without acting up. The last thing that I want to do is send it in and have it returned NPF.
With Biwire cable you are effectively doubling the capacitance and potentially lowering the inductance - which is exactly what Naim amps don’t like (they want low capacitance and moderately high inductance). The Supernait is more tolerant than naim power amps of old, but you don’t want to stray too far from Naim’s recommendations before you may experience issues, in my experience. Did you try yet with a different cable such as NACA5?
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Planning on doing that over the wknd.
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Of course now the SN is not acting up, which is why I’m posting this. I know right after I hit “Reply” it will start humming 
No problem for about 1 week and then…I tried disconnecting the other speaker, hum continued. I then disconnected the right channel, the one with the hum, reconnected but swapped Rt & Lt channels. Disconnecting and reconnecting the right channel cleared the hum. Now with channels swapped at the amp end I will see if the problem returns and which channel it manifests in.
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